The lacunar system of Macracanthorhynchus hirudinaceus, Moniliformis dubius, and Hamanniella tortuosa will be examined in relation to other components (epidermis, circular and longitudinal muscles and praesoma) involved in the construction of the body wall of these Acanthocephalans. The recognized components of this distribution system have changed little since 1850, whereas, we believe them to be much more extensive than currently recognized. The generally accepted model is that the lacunar system consists of a series of channels located only in the epidermis (hypodermis of some authors) of the acanthocephalan body wall and which participate in the distribution of nutrients and perhaps in the regulation of osmotic balance. They may tactly be considered as the circulatory system of the worm. We propose to reexamine this system via standard histological techniques but after the system has been injected (via micropipettes used in conjunction with micromanipulators) with a variety of dyes and ink such as: India ink, Procion birlliant red (H-3BNS), Azure Blue. These as well as Neutral Red and Methylene blue dye solutions will also be injected into living and glycerenated worms via the dorsal or ventral longitudinal lacunar channel. The distribution of the dye will then be observed in live, glycerenated, and fixed specimens. A model of the lacunar system obtained by these techniques will be presented for each species.